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NdisDprAllocatePacketNonInterlocked (Windows Embedded CE 6.0)

  • Статья

1/6/2010

NdisDprAllocatePacketNonInterlocked allocates and initializes a packet descriptor. Because Windows Embedded CE does not support DPC IRQL, all NdisDprXXX functions perform identically to the non-DPR equivalent.

Syntax

VOID NdisDprAllocatePacketNonInterlocked(
  PNDIS_STATUS Status,
  PNDIS_PACKET* Packet,
  NDIS_HANDLE PoolHandle
);

Parameters

  • Status
    [out] Pointer to a caller-supplied variable in which this function returns the final status of the request.
  • Packet
    [out]Pointer to a caller-supplied variable in which this function returns a pointer to the allocated packet descriptor.

Return Value

The following table shows the return values for this function

Value Description

NDIS_STATUS_SUCCESS

The caller can use the packet descriptor returned at Packet.

NDIS_STATUS_RESOURCES

The free list for the packet pool currently has no available entries. A subsequent call to NdisDprFreePacketNonInterlocked will return the given entry to the free list. The variable at Packet is set to NULL.

Remarks

A driver that calls NdisDprAllocatePacketNonInterlocked (and its reciprocal NdisDprFreePacketNonInterlocked) manages the synchronization of its accesses to packet pool internally. The driver allocated such accesses with NdisAllocatePacketPool.

Usually, a driver such as this protects its packet pool with a driver-allocated spin lock. When the driver resumes execution with a locked packet pool, it calls NdisDprAllocatePacketNonInterlocked. After NdisDprAllocatePacketNonInterlocked returns control, the driver releases its spin lock with NdisReleaseSpinLock.

Any packet descriptor allocated with NdisDprAllocatePacketNonInterlocked must be freed with NdisDprFreePacketNonInterlocked except, possibly, when a driver is releasing its allocated resources just before being unloaded. Otherwise, a runtime synchronization error occurs that can cause race conditions to release any packet descriptor with NdisDprFreePacket or NdisFreePacket if that packet descriptor was allocated with NdisDprAllocatePacketNonInterlocked.

If the driver does not manage the synchronization, it should let NDIS manage this synchronization on its behalf by calling NdisAllocatePacket or NdisDprAllocatePacket. In this case, the driver calls NdisAcquireSpinLock before it releases a packet descriptor back to pool with NdisDprFreePacketNonInterlocked and, then, it calls NdisReleaseSpinLock.

Requirements

Header ndis.h
Library ndis.lib
Windows Embedded CE Windows CE .NET 4.0 and later

See Also

Reference

NDIS Library Functions
MiniportDisableInterrupt
MiniportISR
MiniportSynchronizeISR
NdisAcquireSpinLock
NdisAllocatePacket
NdisAllocatePacketPool
NdisAllocateSpinLock
NdisDprAllocatePacket
NdisDprFreePacket
NdisDprFreePacketNonInterlocked
NdisDprReleaseSpinLock
NdisFreePacket
NdisMSynchronizeWithInterrupt
NdisReleaseSpinLock